WFNX had about 21 full and part-time staffers. Now, only a skeleton crew of four people are left, Kadzis said.

“A sale like this … it’s a break up in the family,” he told the BBJ’s Lisa van Der Pool.

Paul Driscoll, the station’s program director, will remain on board.

A source who asked not to be named told the BBJ there is speculation that Clear Channel will switch ‘FNX to a country and western, or Spanish-language talk format.

WFNX is currently owned by the Boston-based Phoenix Media-Communications Group, which also owns the Boston Phoenix, the Providence Phoenix and Stuff Magazine.

If the format changes, WFNX would be the second alternative rock station to leave the Boston FM airwaves. In 2009, WBCN dropped off the FM dial, making way for the launch of 98.5 The Sports Hub.

“Despite its celebrated history, its cutting edge programming, its tradition of breaking new music, its ardent fans among listeners and advertisers, for some time it has been difficult to sustain the station – especially since the start of the Great Recession. And that is why the station is being sold,” Stephen Mindich, publisher of the Boston Phoenix, said in a memo Wednesday.

“WFNX will the file the paperwork necessary to trigger the license transfer with the Federal Communication Commission later today. WFNX will remain on the air during the time it takes to complete the FCC process.”

Clear Channel currently owns four stations in the Boston area, including KISS 108, WJMN-FM, WXKS-AM and WKOX-AM.

“This was a great opportunity to expand our footprint and our listenership in Boston, a key market with millions of fans who love radio as much as we do,” Clear Channel CEO John Hogan said in a statement released Wednesday afternoon,.

“WFNX will remain on the air during time it takes to complete the FCC approval process, and events and concerts — such as the Best Music Poll (June 13th) and the Seaport Six (June 14th) — will take place as scheduled.”